What affects mortgage affordability?
Last reviewed 14 July 2026 · Smarter Mortgage Quotes editorial team
UK mortgage affordability is a mix of income multiples and a forward-looking stress test. Both matter, and the second is where most people are caught short.
Income multiples
Most lenders cap borrowing at 4× to 4.75× combined income. A growing number lend up to 5.5× for higher earners and certain professions (doctors, solicitors, accountants, engineers).
Committed outgoings
Lenders deduct from your income: monthly loan payments, credit card minimums, car finance, childcare, school fees, ongoing maintenance payments. Even a manageable £400/month commitment can shave £25k–£40k off your borrowing.
Dependants
Each dependant (typically children) reduces affordability via a notional cost — usually £300–£500/month per child for most lenders.
Stress tests
Lenders model your payments at a higher rate — often 1–3% above the current SVR or product rate. This is the single biggest reason borrowing capacity has dropped since 2022.
How to improve borrowing capacity
- Clear small loans and credit cards.
- Stop using overdrafts in the 3 months before applying.
- Avoid Buy Now Pay Later — flagged as commitments.
- Use a broker who knows which lender favours your profile.
- Consider a longer term — lowers the stress-test payment.
Estimate a broad borrowing range with our borrowing calculator, or speak to an adviser if you need lender-specific information.